When I went to club maker training at the Golfsmith HQ, they were monkeying around with the lightest shaft they could come up with. They lightened it by scraping all of the paint off with a utility knife.
It does work. It’s how I take paint off the tips. That’s the method they taught us. The paint comes off but the graphite is not damaged. Hold the blade at 90 degrees to the surface. Straight up and down. Scrape back and forth.
Sanding is a bad idea. You will end up removing graphite.
And, I was also thinking about this in the past 24 hours, because of the electric yellow shafts.